Psychology - Research Methods - Experimental Designs Flashcards
Experimental designs
how the participants are organised within the experiment. There are three main types of experimental designs
What are the three main types of experimental designs?
Independent groups, Repeated measures, Matched pairs
Experimental condition
a group of people who are exposed to the independent variable
Control condition
group receives no treatment and are used as a base line level to compare results against
What are controls in an experiment?
Randomisation, Standardisation, Random allocation
randomisation
use of chance in order to control for the effects of bias when deciding the order of conditions. This is important if you are using a repeated measures design and the same participants are taking part in two different conditions.
Standardisation
Using exactly the same formalised procedures and instructions for all participants in a research study - this improves the reliability of the study
Random allocation
An attempt to control for participant variables in an independent groups design which ensures that each participant has the same chance of being in one condition or the other
Independent group design
Different participants used in each of the conditions. So each group of participants are independent from one another. Participants are usually randomly allocated to each condition to balance out any individual differences.
What are the advantages of independent groups design?
- Order effects will not occur as there are different participants in each condition, - Chance of demand characteristics reduced as participants only take part in conditions that influences their performance or behaviour - Participants aren’t lost between trials as they only take part in one condition and then leave
What are the disadvantages of independent group designs?
- More participants are needed compared to a repeated measures designed - Always a chance that the different results gained are due to individual differences rather that manipulation of the independent variable
Repeated measures design
each participant is tested in all conditions of the experiment.
What are the advantages of repeated measures designs?
- No individual differences between conditions so only measures effect of IV on DV - Half as many participants needed compared to individual group design
What are the disadvantages of repeated measures design?
- Order effects may affect results, but counter balancing could be used - Demand characteristics are more likely to occur using repeated measures designs as participants are involved in the entire study and they may guess aim of the study
counterbalancing
when half the participants do condition A first and then condition B second and the other half of the participants do condition B first and condition A second. Changing the order of the tasks helps to reduce order effects and negative impacts on data collection.
Matched pairs design
different participants are used in all of the conditions, just as with the independent groups design. However, participants in the two groups are measured on characteristics important for that study
What are the advantages of matched pairs designs ?
- less risk of order effects using matched pairs design as participants only take part in one condition - Individual differences are less likely to occur as the groups have been closely matched on specific characteristics
What are the disadvantages of matched pairs designs?
- Twice as many participants are required compared with a repeated measures design, researchers need to gain access to a large number of participants - Matching process is difficult and time consuming and individual differences cannot be completely controlled and removed
Order effects
occurs when participants responses in the various conditions are affected by the order of conditions to which they were exposed
